Apple tree `Co-op 38`

ABSTRACT

The cultivar of the present invention, designated `Co-op 38`, is a new and distinct cultivar of apple tree (Malus×domestica Borkh.). It was discovered in October of 1980 at West Lafayette, Ind., in the course of an attempt to develop improved apple cultivars with high fruit quality and resistance to Venturia inaequalis (Cke.) Wint., the causal agent of the scab disease of apple. The tree is a seedling of known parentage planted in May of 1973 in the HE Block of the apple breeding orchard on the Hinsley tract of the Purdue Horticulture Research Farm, West Lafayette, Ind. In the above mentioned block, its position was Row 4, Tree 16, having the designation PRI 2750-6 in the breeding records.

BACKGROUND OF THE INVENTION

The present new cultivar, `Co-op 38`, also known as `Goldrush`, wasproduced from crossing `Golden Delicious` as the seed parent and theselection Co-op 17 (PRI 1661-1) as the pollen parent in 1972 at Urbana,Ill. The new cultivar carries the genetic factor V_(f) inherited fromMalus floribunda Sieb. 821 that renders it highly resistant to infectioncaused by Venturia inaequalis. For more than twenty years, trials ofapple cultivars containing V_(f) in every humid production area of theworld have shown no breakdown of this resistance. The presence of thisfactor in `Co-op 38` has been demonstrated by controlled greenhouseinoculation tests of the seedling and thirteen years of observation ofthe seedling and propagules under natural conditions for infection inthe field at the West Lafayette site and at multiple sites in the U.S.and abroad for several years. The complete pedigree is shown in FIG. 3.

The new cultivar produces a moderately vigorous, slightly upright,spreading, sturdy branched, semi-spur tree, similar but slightly moreupright and less vigorous than `Golden Delicious`. Fruits have atendency to be borne singly on short to moderate length spurs, on secondand third year wood, and hang well on the tree. `Co-op 38` is fieldimmune to apple scab. Based on field observations it is moderatelyresistant to fire blight (incited by Erwinia amylovora (Burr.) Winslow),and has a high level of resistance to powdery mildew (incited byPodosphaera leucotricha (Ell. & Ev.) Salm.) It is susceptible tocedar-apple rust (incited by Gymnosporagium juniperi-virgininae(Schw.)).

Flowering occurs late in the bloom season, after `Golden Delicious`. Thefruit is best suited for use out of storage in winter and spring. Thedessert quality is very good to excellent and reaches its peak in latewinter and spring. Fruit retains characteristic quality (flavor andtexture) for 7 months or more in refrigerated storage at 1° C.

After observations, the selection was asexually propagated by graftingon seedling, EMLA-111, and EMLA-7 rootstocks at the above notedLafayette site. Preliminary observations indicate that grafted materialhas retained the described characteristics after propagation.

BRIEF DESCRIPTION OF THE FIGURES

The first figure is a photograph showing the leaves and fruit of `Co-op38`.

The second figure is a photograph showing the fruit of `Co-op 38` on alarger scale.

The third figure, entitled `Pedigree`, is a schematic diagram showingthe pedigree of `Co-op 38`.

DETAILED DESCRIPTION OF THE NEW CULTIVAR

The accompanying color photograph shows a typical example of fruit andfoliage of `Co-op 38`. The following is a detailed description of thenew cultivar with color designations according to the 1966 HorticulturalColour Chart (Wilson) issued by The Royal Horticultural Society ofLondon.

FLOWERS

Corolla: Average of 43 mm in diameter at anthesis.

Petals: 14 mm×21 mm.

Color: Rose Bengal; 25/1 to Magenta 27/1 (bud) fading to white marginedor patterned with Rose Bengal 25/4 to Magenta 27/1 or lighter (openflowers). Adaxial surface of petals has more color and distinct patternsthan abaxial surface. None of the petals are totally white, even atpetal fall.

FRUIT

Shape: Ovate, regular.

Length:width ratio.--0.94.

Size: Average diameter is 70 to 76 mm.

Color: Greenish at harvest, developing 100% self-yellow color in storagefrom Lemon Yellow (Plate 4/1) to Saffron Yellow (Plate 7/2). Developsheavy blush on sun exposed side of fruit.

Skin: Smooth, non-waxy, tender, thin to medium in thickness; veryconspicuous, russetted, round to stellate, scattered dots, not rough tothe touch.

Stem: Medium to long, thin to medium.

Acute, medium depth, medium width, occasional russet.

Basin: Medium depth, medium breadth, sloping sides, regular surface.

Calyx: Persistent, open, erect to recurved.

Calyx tube: Conical.

Stamens: Median.

Core-lines: Clasping.

Core: Median, usually closed, medium sized.

Carpels: Round, emarginate, smooth.

Seeds: Full compliment, acute, non-tufted.

Flesh:

Texture.--Medium coarse grained, firm, very crisp and breaking.

Quality.--Very spicy and spritely acid at harvest; spicy, rich fullflavor; very good to excellent quality which improves with moderation inacidity in storage; Brix at ripeness generally exceeds 12%.

Color.--Indian yellow (Plate 6/3).

Maturity season: October 20 to 30 at West Lafayette, Ind.; three weeksafter `Delicious`.

On-tree storage: Good on-tree storage characteristics with no tendencyto develop water core.

Processing quality: Fruit has good processing quality.

Keeping quality: Very superior; quality improves in storage and isexcellent in regards to both texture and flavor for at least 7 months at1° C.

Use: Winter dessert apple, appropriate for medium and long term storage.

TREE

Tree: Slightly upright, moderately vigorous, limited branching,semi-spur bearing habit. Fruits are borne singly on short spurs and hangwell on the tree even when over-ripe; some biennial tendency.

Leaves: Ovate to oval; serrate to double serrate margins; apex acute toacuminate, base acute to rounded; length to width ratio=1.87. Leafpetioles show anthocyanin pigmentation, which can be intense in tissuesexposed to the sun.

Pruning training requirements: Tree has strong central leader withmoderate growth; because of moderate growth minimal pruning and trainingwill be required.

Branch angles: Commercially desireable branch angles, 70 to 90 degreeswith little tendency for bark inclusion in crotch.

Pollination: Requires cross pollination for optimum yield.

Productivity: Moderately productive.

Thinning: Will require thinning to achieve optimum size.

Bark: Current year stems are Maroon (1030) on sun-exposed surface, PeaGreen (61) on underside of new growth, lenticels on one-year-old woodare raised, about 1.0 to 1.3 mm in length, round to oblong, Apricot609/3; lenticels on 5-year-old trunks are rough, slightly irregular,often circular, as large as 7×4 mm, typically 3 mm in length, Apricot609/2.

We claim:
 1. The new and distinct apple tree substantially as shown anddescribed, characterized by resistance to apple scab, fire blight, andpowdery mildew; extremely long storage life; attractive appearance; verygood to excellent dessert quality which reaches its peak after storage;extremely crisp and breaking flesh texture; and maturity approximatelythree and one half weeks after `Delicious` and six weeks after`McIntosh`.